I believe this is a very damaging act. Your internet activity should be private, just like your library card activity and your movie rental activity.

There are a few things you can do to protect your privacy from your ISP today. See below for more of my favorite general privacy and security links.

I always recommend using SSL/TLS as much as possible. Install the EFF's HTTPS Everywhere browser plugin. This is good but it will not completely blind your ISP as they will still see the IP address and domain names of who you are contacting.

For better protection, use a reputable VPN service. This is not too complex but it will cost you money. I'm still investigating my VPN options, so I'm reluctant to make a recommendation now. I'd prefer to set up a VPN on my home router so all my devices are protected when at home. I'd also like to have the VPN exit in Europe to get GDPR privacy protection.
Here are a few links to get you started:
ARS Technica's in-depth article on How to stop ISP's from selling your data.The impossible task of creating a "best VPNs"list
TechRadar 10 best VPNs